1. Field of the Invention
This invention is in the field of automatic washing machines employing vertical axis agitators which oscillate to provide a tumbling motion to the clothes contained within the machine and provides an agitator construction which is particularly useful with large or heavy clothes loads to improve the movement of the clothes within the machine and thereby the washing action.
2. DESCRIPTION OF THE PRIOR ART
It has long been appreciated that the most efficient clothes movement pattern for washing clothes within an automatic washing machine having a vertical axis agitator is a pattern which provides a rollover of the clothes which involves moving the clothes down the agitator barrel, then radially outward from the oscillating agitator vanes, upward along the wall of the tub, and inward to the barrel. Conventional washing machines are reasonably proficient in achieving this type of rollover pattern when light loads are being washed, but not with heavy loads. When the washing basket is tightly packed with clothes, the load crowds the agitator and the basket area. A conventional oscillating agitator has difficulty in attaining any kind of a rollover to the clothes load under these conditions. The conventional-type agitator then scrubs merely the bottom portion of a tightly-packed heavy load, resulting in a very poor uneven cleaning action.
There are a few examples in prior patents of agitators which move in separate paths during a washing operation. For example, the Bryant U.S. Pat. No. 1,834,936 suggests dual agitator members which are reciprocated in opposite directions within the tub, the object being to create a violent water action.
The Krolzic U.S. Pat. No. 3,678,714 assigned to the same assignee as the present invention describes a washing machine assembly including a pair of agitators, the two agitators being coupled together for mutual oscillation, but having cam means or the like provided between the two agitators to effect a vertical reciprocation of one with respect to the other during such oscillation.
Prior art patents disclose agitators with spiral vane elements. For example, Dyer U.S. Pat. No. 2,331,897 discloses a washing machine having an agitator provided with a spiral vane on an upper portion, the agitator rotating at motor speed during washing.
Krolzick U.S. Pat. Des. 196,194 assigned to the same assignee as the present invention shows an agitator for a laundry machine wherein the ornamental design for the agitator includes a spiral vane arrangement.
Geldhof U.S. Pat. No. 2,734,367, assigned to a predecessor of the assignee of the present invention, shows an agitator for a laundry machine wherein the agitator includes spiral vanes which extend in the form of radial vanes on their lower edges with radial projections or vanes extending intermediate the spiral vanes.